1. Field of the Invention
The present invention relates to the manufacture of laminated glass plates or glazings and in particular to an apparatus for the assembly of the components of a laminated glass plate by pressing and in particular by calendering, i.e. by passing the stack of said components, which is also referred to by the term glazing in the remainder of the description, between upper and lower pressing means.
2. Description of the Related Art
The known calendering apparatus, e.g. described in French patent 2 053 104, are generally equipped with two series or rows of pressing rolls or rollers. One series of lower rollers are arranged in juxtaposed manner and their position can be regulated independently so as to obtain a curvature corresponding to the desired transverse curvature, which is generally the mean or average curvature of the glazing. A series of upper rollers is arranged substantially in the same way. In the known apparatuses, each of the two series of rollers is mounted on a transverse beam belonging to a frame able to pivot about a horizontal axis, the assembly constituting a moving means, in such a way that the rollers remain substantially perpendicular to the glazing throughout the assembly operation.
During the passage of the glazing or glass plate between the rollers, the position of the latter must vary in order to follow changes in the transverse curvature of the glazing. To this end, European patent 0 189 345 proposes a calendar using pneumatic jacks giving the rollers a considerable flexibility in following the curvature of the glazing. In this so-called "floating" calender, the compression chambers of the jacks of the upper rollers and those of the jacks of the lower rollers are linked and the pneumatic pressure exerted on a pressing or pressure roller is equal to that exerted on a back-pressing or back-pressure roller.
These apparatuses are generally suitable for the assembly of glass plates having a relatively small and regular transverse cambering which is substantially the same over the entire length of the glazing. However, in the case of glazings with more complex shapes, particularly those having a very deep cambering in the transverse section and/or irregular over the length of the glazing, said apparatuses are not always satisfactory, because they are not sufficiently flexible to be able to follow all the large curvature modifications. If the pressure of the rollers is inadequate, there occurs an inadequate or only slightly homogeneous adhesion of the components of the glazing or, conversely, if the pressure is too high the glazing may fracture.
In order to increase the flexibility of the apparatus, Applicant has proposed using rollers having a limited width, while increasing their number. However, this proposal leads to another problem, namely that of increased overall dimensions of the pneumatic jacks juxtaposed in the vertical plane passing through the pressing line.